1. Field of the Invention
The present invention relates generally to the field of electrical timers that connect to a building's electrical system to control electrical current supplied to one or more electrical appliances. More specifically the present invention relates to such timers that include at least one electrical socket adapted to receive the electrical current from the electrical system and for plugging-in one electrical appliance. A time selector switch is provided. A controller makes an electrical circuit between the electrical system and the electrical socket for at least one preset time period upon actuation of the switch.
2. Description of the Prior Art
Electrical timers are used in households and businesses to control the operation of electrical appliances. For example, people often connect timers to operate lights when the are on vacation so thieves will think they are still at home. These timers typically plug into conventional electrical wall outlets and the appliance plug into the timer. The timers have a mechanical or electronic controller that operates an internal switch in accordance with a 24 hour schedule. A user sets intervals at which the internal switch operates to turn on and off electrical current to the appliance on the 24 hour schedule.
Some timers require the user to set on and off intervals using push pins while others allow timing to be set via microprocessor control. Some timers require setting of time-of-day and/or time-and-date prior to operation. Others use the controller to allow varied intervals rather than a repeating 24 hour schedule of appliance operation. Many timers utilize a microprocessor for timing functionality powered by an internal battery. This allows operation to continue on-schedule regardless of an electrical power outage when the power is restored. In other timers, the microprocessor is powered by electrical current supplied by the wall outlet such as through a step-down transformer and rectifiers. These timers stop timing during the power outage and resume when the power is restored. However, such timers thus are out-of-synch with the actual time which is problematic.
There have been various electrical timers patented over the years. For example, an electrical timer having scales for setting switching times and time-of-day is disclosed in U.S. Pat. No. 5,715,214 issued to Svarnias on Feb. 3, 1998. A window exposes only a portion of one of the scales to help users to set the time-of-day of the timer. In one aspect, the window is located in a cover that hides all but a portion of the time-of-day scale. According to a further aspect, the switching-times scale and the time-of-day scale are located on a dial rotatably mounted on a timer housing that includes a suitable electrical plug, an electrical receptacle, and an electrical switch operable with the scales.
U.S. Pat. No. 5,309,032 issued on May 3, 1994 to Nilssen discloses a plug-in timer that has a set of input terminals and a set of output terminals. A contactor is operable to make and/or break electrical connection between the sets of terminals in accordance with a pre-set 24 hour program. The timer has a clock and is powered by a battery. The contactor is actuated by a miniature DC motor through a gear and cam arrangement. Operation of the motor is controlled by a programming-and-control device, which provides power from the battery to the motor in accordance with the 24 hour program. The 24 hour program can be modified using a keyboard and a numeric display. Operation of the timer is totally independent of the line power and is not be affected by a power failure.
While the prior art electrical timers are generally adequate for the purposes intended, they have significant shortcomings. Firstly, most timers are unduly complicated to set up and operate, requiring setting to the local time then setting the intervals at which to turn on and off electrical current to the appliance. Secondly, most timers utilize a recurring 24 hour schedule which may not be desirable, depending on the particular application. Thirdly, none of the timers allow spur-of-the-moment appliance activation for a predetermined time period.
It is thus an object of the present invention to provide an electrical timer that is simple and uncomplicated to set up and operate, not requiring setting to the local time.
It is another object of the present invention to provide an electrical timer that does not utilize the recurring 24 hour schedule.
It is yet another object of the present invention to provide an electrical timer that allows spur-of-the-moment appliance activation for a predetermined time period.